1. Field of the Invention
This invention relates in general to machinery for making corrugated paper, and in particular to an air pressure cleaning device for glue roller grooves.
2. Description of the Prior Art
Corrugated paper is a relatively stiff, heavy paper, used in cardboard boxes and the like. This type of paper has a layer of corrugated paper bonded to smooth layers of paper on each side.
In one machine for performing the corrugation, an upper corrugating roller, with corrugations on a cylindrical surface, intermeshes with a lower corrugating roller. A web of paper is fed between them, being corrugated as it passes through them. After corrugating, the corrugated web proceeds more than halfway around the lower corrugating roller. To keep the corrugations of the paper located within the corrugations in the lower corrugating roller, a plurality of curved fingers are mounted next to the lower corrugating roller. A glue roller contacts the corrugated paper at this point to apply glue. Circumferential grooves are formed in the glue roller to accomodate the fingers. A pressure roller receives a second web and presses it to the corrugated web after the corrugated web has received the glue.
Glue is applied to the glue roller by partially submerging the glue roller in a pan of glue. As a result, the glue gets into the grooves. This glue tends to build up on the fingers, causing detritus to collect on the fingers. This may result in wide dry streaks on the corrugated paper where no glue is placed. The wide dry streaks may cause the paper to break along that line. Consequently, build up of detritus must be controlled.
In the prior art, glue is cleaned from the grooves by a second set of fingers mounted in the grooves of the glue roller. These glue roller fingers, are thin metal members inserted into the grooves immediately above the glue pan. They wipe the glue from the grooves prior to the retaining fingers.
One disadvantage of the glue roller fingers is that they wear since they are located in sliding contact with the grooves. They must be changed periodically, this procedure being costly and time consuming. Also, the glue roller fingers tend to pick up detritus that cannot be easily removed. If unchecked, too much of the glue will be wiped from the grooves, leaving an undesirable wide streak on the paper.